posted on 2012-12-18, 00:00authored byYu Wang, Yungwan Kwak, Johannes Buback, Michael Buback, Krzysztof Matyjaszewski
Atom transfer radical polymerization (ATRP) equilibrium
constants
(KATRP) were measured during polymerization
of methyl acrylate (MA) with CuIBr/CuIIBr2 in either dimethyl sulfoxide (DMSO) or acetonitrile (MeCN)
in the presence of either tris(2-pyridylmethyl)amine (TPMA) or tris[2-(dimethylamino)ethyl]amine
(Me6TREN) as the ligand and with ethyl 2-bromopropionate
as the initiator. The ln(KATRP) values
changed linearly with the volume fraction of solvents in the reaction
medium, allowing extrapolation of the values for KATRP to bulk conditions, which were 2 × 10–9 and 3 × 10–8 for TPMA and Me6TREN
ligands at 25 °C, respectively. The temperature effect on KATRP values was studied in MA/MeCN = 1/1 (v/v)
with TPMA as the ligand in the temperature range from 0 to 60 °C.
The KATRP values increased with temperature
providing ΔH = 36 kJ mol–1 in MeCN.